About P21 HUD: Features: Display the driving data such as speed, speed, fuel consumption, water temperature, voltage, etc. on the front windshield to avoid the insecurity caused by the driver looking at the instrument while driving. The driver can read the driving information in real time and keep the HUD in the best condition at any time.This product is a dual system: after power on, choose the language you are familiar with, choose the OBD or GPS system, and automatically enter the last selected system after 5 seconds of no operation.11 large interface functions, you can switch at will.A variety of operating interface modes and colors can be switched freely, bringing you more fun and a sense of technology.Specificaitons Color: BlackProduct size: as shown Material: ABS+PCWorking voltage: 11V~18Vdc (12Vdc/200mA)Photosensitive components: automatically adjust the brightness with the surrounding environmentLanguage: CN Simplified Chinese / TW Traditional Chinese / EN English, etc.SettingModes: System Sound Settings: ON to turn on the alarm sound / OFF to turn off the alarm soundSpeeding reminder: alarm when the vehicle speed reaches the set default value of 150km/h, the setting range is 5-200km/hEngine temperature alarm: alarm when the water temperature reaches the set default value of 120C, the setting range is 50-200Engine speed alarm: alarm when the speed reaches the default value of 6000r/min, the setting range is 1000-8000Voltage alarm setting: alarm after the voltage is lower than the set default value of 10.5v, the setting range is 10.0-15.0vSpeed error adjustment: adjust the parameter value when there is an error between the speed and the instrument panel (for example, the instrument displays 100 Km/h, the device displays 105 Km/h, and the dial wheel is turned up to adjust the parameter value to 102)Speed zero setting: when the vehicle speed does not